Clean machine

Some University of Minnesota Duluth (UMD) students spent the summer thinking about snow. Members of the Clean Snowmobile Club, they were looking for ways to make their sled cleaner, quieter, and more fuel efficient as they prepare for the 2019 SAE Clean Snowmobile Challenge, March 4–9.

Judged on performance, design, and practicality, the UMD team placed second among the gas-powered machines in 2018. Gifts from donors, including Polaris, Amsoil Inc., DENSO, and BorgWarner, funded the sled, parts, materials, and travel to Houghton, Michigan, for the challenge. “We really can’t do what we do without support from our gracious donors and their awesome contributions,” says club president Jake Krabbenhoft.

Formula for a winning sled

1

Anti-stab track wheels to lessen noise and provide more power. The UMD students' work resulted in a 6 dBa drop in noise from 87 dBa to 81 dBa.

Right: Sound improvement

Snowmobile photo: MTU/KRC

2

Sound-deadening coating on underside of tunnel

3

Stand-alone engine control unit to support closed-loop fuel control (adjusts fuel for optimal combustion). Changes to the 2018 sled saw fuel mileage increase from 13.5 mpg (stock) to 15.1 mpg.

4

Cleaner, more efficient four-stroke engine replaced stock two-stroke engine. This and other changes led to a 97 percent reduction in carbon monoxide emissions (from stock), and 92 percent fewer hydrocarbons and 73 percent less nitrogen oxide being emitted.

5

Custom intake and exhaust system to reduce noise

Right: Exhaust silencer

6

Changes for the 2019 challenge include:• Variable valve timing to
improve fuel economy and reduce nitrous oxide, one of the most harmful
emissions• Redesigned engine mounts
and larger oil reservoir, lowering the engine for better handling• New rear-exiting exhaust
with resonator tube to further cancel noise